[mythtv] Recording Profiles

Joseph A. Caputo jcaputo1 at comcast.net
Wed Apr 16 14:55:13 EDT 2003

Actually, I have the opposite problem...

I was watching LiveTV, which is set up for RTJPEG 480x480 at 255, as it's less
CPU-intensive, but gives larger files.  Just before a scheduled recording
was about to begin (on the same channel I was watching), the dialog popped
up asking me what I wanted to do.  I chose 'Record & Watch while it
records'.  In a few seconds, I detected a little stuttering (presumable as
it changed from the ringbuffer to a file, whatever).  My 'Default' profile
is set for MPEG-4, 480x480 at 2200 (scaled bitrate) However, after the program
was done, I went to delete it, and noticed that the file size was in line
with an RTJPEG file rather than an MPEG-4.  (The file was about double the
size of most MPEG-4 recordings of the same length, but about the same size
as an equivalent RTJPEG recording).

So, when switching from LiveTV -> WatchingRecording, maybe it's not
switching profiles?

In your case however, I would think it would be impossible to switch
profiles after a recording has started, without losing part of the file...
you can't have the backend switch the encoding codec/paramaters in the
middle of an in-progress recording (I wouldn't think).  Think about it...
you have a file whose header says "MPEG-4 480x480 at 3300".  Then in the middle
of the file, the data is suddenly in "MPEG-4 320x240 at 2200", or worse yet,
"RTJPEG 480x480".  Your player would probably die.  Not to mention the
backend problems of building a seek table, cutlist... you get the gist.

Of course, I really don't know anything about encoding/decoding processing,
so don't take my word for it.  Would anyone care to confirm/deny this?

-Joe C.

> -----Original Message-----
> From: mythtv-dev-bounces at snowman.net
> [mailto:mythtv-dev-bounces at snowman.net]On Behalf Of Brian A. Vance
> Sent: Wednesday, April 16, 2003 1:15 PM
> To: mythtv-dev at snowman.net
> Subject: [mythtv] Recording Profiles
> A question I've been meaning to ask for a while now:
> Presumably most people have lower settings for 'LiveTV' than they do for
> 'Default'.  This is because it takes s bit more juice to watch a program
> while you are recording it (LiveTV)...  so my questions is this...  What
> if I begin recording at 8:00 (using the 'Default' recording profile)
> then start watching the recording at 8:15.  Once I start watching at
> 8:15 does the 'LiveTV' recording profile kick in, allowing me to watch
> without having the system fall to it's knees trying to record with the
> 'Default' recording profile and watch the program at the same time?  If
> not, shouldn't this be the case?
> -Beev

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